Appearance and Occurrence
Graupel is precipitation in the solid state, one of the forms in which ice can fall from the sky. Graupel grains are round or conical in shape and have a diameter of 1 to 5 mm.
There are two types of sleet. Hoarfrost is opaque white grains with a snow-like texture. The grains can be easily compress. They often break when they hit a hard surface. Hoarfrost occurs in winter at temperatures below 0 degrees.
White grains and a ruler
Frost sleet from the “textbook”. (Source: MeteoSwiss)
Frost sleet has a cloudy core surround by a clear layer of ice, making it semi-transparent. The grains are difficult to compress. Frost sleet is often wet because it usually falls at positive temperatures. Frost sleet is most commonly seen in spring, as was the case yesterday.
Whitish, semi-transparent, wet grains on slab floor.
Frost hail yesterday in Uster. (Source: Meteo reports/app)
creation
Sleet falls from thunderclouds or from large cumulus clouds. It is philippines phone number library therefore a convective form of precipitation and only occurs in short showers.
In convective clouds there is usually water in different forms: liquid, solid and supercool, i.e. liquid water that is below 0 degrees. When supercool water freezes onto (thaw) snowflakes or ice crystals, sleet is form. The details of the processes that occur go beyond the scope of this blog (keyword: cloud microphysics).
Flat small cumulus clouds over hills and villages
The convective clouds today were clearly too small to produce the goal is to convert visitors into long-term customers any precipitation. (Source: bantiger.roundshot.com)
Difference to other forms of precipitation
Hoar sleet is often confus with snow. This is not surprising, as hoar alb directory sleet looks similar to snow and often occurs together with snow. The difference lies primarily in the shape: hoar sleet is round grains, snow falls in the form of ice crystals or irregularly shap snowflakes. But there are also snowflakes that consist of ice crystals and hoar sleet. There are also differences in how they are form: hoar sleet only forms in convective clouds, snow can fall from various types of clouds.
